The present invention relates to a disc drive microactuator, and more particularly to a high resolution head positioning mechanism that includes a lowstress microactuator cradle for improving the stroke and torsional gain characteristics of the microactuator.
The density of concentric data tracks on magnetic discs continues to increase (that is, the width of data tracks and radial spacing between data tracks are decreasing), requiring more precise radial positioning of the head. Conventionally, head positioning is accomplished by operating an actuator arm with a large-scale actuation motor, such as a voice coil motor, to radially position a head on a flexure at the end of the actuator arm. The large-scale motor lacks sufficient resolution to effectively accommodate high track-density discs. Thus, a high resolution head positioning mechanism, or microactuator, is necessary to accommodate the more densely spaced tracks.
One promising design for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional lower resolution actuator motor, thereby effecting head positioning through dual-stage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning. One such design is disclosed in U.S. application Ser. No. 09/289,024 filed Apr. 9, 1999 for "Unitary Synchronous Flexure Microactuator" by R. Kant and F. M. Stefansky, which is hereby incorporated by reference. This design includes a microactuator cradle that carries the entire micro-electronic machine (MEM) that supports the slider and generates high resolution displacement of the slider. The microactuator cradle is mounted a load beam connected to an actuator arm for coarsely positioning and supporting the entire cradle and slider structure over the surface of a disc. There is a continuing need in the art for improved microactuator designs such as the one disclosed in the aforementioned application, to achieve desired characteristics for operation in a disc drive system.